Lithium Carbonate Supplies Abound!

One of the worries I often hear about opposition to electric cars is that we’re trading one resource for another – oil for lithium. The list of countries with large lithium deposits aren’t overtly hostile to the US and its allies, however they are further left than we are (but who isn’t really?). Evo Morales of Bolivia has already stated he didn’t want outside companies to come in to Bolivia and take the lithium. But do we have enough from other sources to provide the number of lithium-ion batteries we’ll need to power the cars of the future?

An article at Seeking Alpha discusses a lithium conference held in Chile this year. At this conference, the future of lithium demands and reserves were discussed. The geologist who authored the article estimates that there are 30M tonnes of elemental lithium and 160M tonnes of carbonate (Li2CO3) – the actual material used in the production of lithium ion batteries.

Beyond that, there is a fairly high confidence of accuracy of these claims. Drilling performed in a mine along the Oregon/Nevada border indicated that an estimate from years ago was within 10% of a recent drilling. Western Lithium is focusing in on a single deposit of lithium of around 770,000 tonnes (1.5B lbs.) in Kings Valley, Nevada, with an estimated 11 million tonnes total (25B lbs.). With the recovery estimated at 85% for this area, that’s 9.35M tonnes of carbonate. They estimate producing 20,000 tonnes of LCE per year by 2013, and at a rate of 0.6kg/kWh of battery, it is enough for 3.3 million 10kWh battery packs per year. The most recent peak in the 1990s there were only 8.7M passenger cars sold (not including SUVs, trucks, etc), so a 10kWh battery coupled with sufficient technologies to allow 40 miles per charge (increased power/kg, depth of discharge) would allow 38% of cars manufactured to be PHEVs if the market and prices allowed, and this is just from one site located in northern Nevada, accessing only a fraction of what the site is expected to produce.

Down in southern Nevada near Tonapah, there is the only existing lithium brine recovery operation in the US in Clayton Valley, Nevada, where estimates range from 2 million to 20 million tonnes of LCE. One more valley over, there is the Fish Lake Valley, which has similar concentrations of lithium as Clayton Valley. The Clayton Valley site currently produces 5,700 tonnes annually, or enough for about 594,000 16kWh battery packs per year – the first three or four years of Volt production wont exceed 250,000 units. And I still haven’t left the great state of Nevada.

So what does 160M tonnes of lithium carbonate equivalent (LCE) equate to in batteries? With current production techniques, 0.6kg of lithium carbonate will be used per kWh of battery storage capability, and 1 kg of lithium carbonate is equivalent to 0.1875 kg elemental (pure) lithium. At 0.6kg LCE per kWh, recovering 50% of the estimated 160M tonnes of LCE would result in 13.3 Billion 10kWh batteries, or 3.8B 35kWh battery packs for battery electric vehicles. There are about 1B vehicles on the planet now, and factoring in growth to 2B by 2030, it would take about 60 years to go through that amount of lithium (assuming batteries last 10 years). When you combine this with lithium recycling, the supplies are enough to last us well until we find the lithium-ion replacement technology.

So what about recovery? Even by 2030 when plug-ins and pure electric cars are 90%+ of the sales (as estimates), that would mean an annual US vehicle production of 12 million vehicles per year would require almost 11M vehicle battery packs, at an average of 15kWh each, that’s 165 million kWh, or 99 million kg, or 99,000 tonnes just for the US. Worldwide, by 2020, its estimated that lithium-ion batteries for vehicles will require at most 70,000 tonnes per year, while various mining industry groups claim to be able to ramp to the high figures needed just themselves. This area appears to be well covered.

Finally is cost. Even at $250/kWh (the 2020 industry target price), lithium’s only about 2% of the battery price. The price for LCE is about $8/kg, or about $4.80/kWh, even doubling it doesn’t have a much of an effect on the price – from 2% to 4% of total cost in 2020.

We will still need to figure out what will come after lithium, though some companies are already laying the groundwork for the post-lithium era. But the doomsayers don’t have much of a leg to stand on, and we still haven’t got into harvesting lithium from seawater (at a first-generation technology price of $22-32/kg, with enough lithium for 18 trillion Tesla Roaster battery packs).

A123 Battery Technology – LiFePO4

A123 systems has been a big name in batteries since the plug-in revival started again two years ago. One unique property of the A123 batteries is that instead of prismatic cells (that is, rectangular prism), they’re cylindrical, like the AA batteries that go in your digital camera.

Their chemistry of choice is lithium iron phosphate, or LiFePo4. Their current premier cell that they have specifications available for is the ANR26650M1A, or just M1 cell. This cell packs about 7.6Wh in one cylinder about 6.5cm tall (2.55 inches) and 1.5cm in diameter. That means you’d need 2,100 cells to make a 16kWh battery, and that many cells would provide more than necessary power to supply the electric motor.

One of the rumored reasons why GM chose LG Energy over A123 is that because A123 was unable to produce prismatic cells, and GM needed prismatic cells to fit the necessary 16kWh in the Volt without taking up any more room than they already are. However, this is in direct conflict with Chrysler’s assertion that they are working with A123 on a prismatic cell. The M1 is also the cell that the could be in the Raser Electric Hummer H3, based on a reference to the cell in the H3 promotional video.

A123 is happy to tout their cycle life – their specification sheet has a graph showing that at 45°C (113F, not an unreasonable temperature to keep batteries at during usage) the cycle life exceeds 1000 cycles and maintained just under 90% of its original capacity. At the steady rate of decline showed on the graph, it appears the battery could get up to 1,750 cycles until capacity was 80% of original capacity at 1C charge and 2C discharge.

We’ll see if Chrysler can make it out of Ch 11 and the merger with Fiat to create these electric cars they’ve planed on making, or if A123 gets a better dance partner (Ford?) before the prom is over.

Analyzing Battery Performance Characteristics

There are several metrics to how batteries are measured. And those metrics play various roles in determining how well the batteries would (or wouldn’t) perform in an electric car. From standard hybrids to plug-ins and pure electric vehicles, they all have different battery needs.

We’ll start with the basic measurement of capacity. Your vehicle’s fuel tank might hold 19 gallons of fuel, and the battery equivalent is energy, measured in kilowatt-hours, or kWh. Sometimes the figures are offered in Amp-hours or Ah, to get kWh multiply that figure by the cell’s nominal voltage.

A laptop battery might have around 0.05kWh of energy, while the Chevy Volt has 16kWh, so you can image how many laptop batteries you would need to put in a car to get 16kWh. The biggest battery in a vehicle is the Telsa Roadster’s with 53kWh.

It is estimated that a small sedan would use about 200Wh per mile of driving, and a large SUV would use around 400Wh per mile. Those are average figures, with regenerative braking decreasing city driving figures and highway driving increasing those figures. As the vehicle weight go up, and as your driving speed increases, the amount of energy needed per mile goes up as well. Obviously, increased weight requires a greater force, and aerodynamic resistance increases as the square of speed, so the force required to cut through the air at 70MPH is twice of the force at 50MPH.

So how does all that energy get from the battery to the electric motor? It goes through an inverter to convert the DC (direct current) energy into AC (alternating current) energy to power the motor. This raises the issue of how much power can those batteries deliver at any given moment.

Reading from a battery’s spec sheet, you’ll usually find a pulse power rate. This is measured in W (for each battery) or W/kg, and is the short-term power the battery can put out. Combining this with the total number of cells or total cell weight will determine the maximum power the batteries can deliver to the motor. The motor in the Tesla Roadster is 185kW, and the Volt’s motor is about 110kW.

One of the most important battery characteristics is the energy to weight ratio, usually called energy density, measured in Wh/kg. This is the battery’s usable energy divided by the weight of the battery. This is the most critical factors when it comes to examining batteries – the energy density determines how heavy the battery is, which is a very important factor when it comes to automobiles. Closely correlated to energy density is the energy to volume ratio, measured in Wh/L, this determines how large the batteries are.

Today, automotive lithium ion batteries are approximately 70-100Wh/kg. This means for each kWh of energy storage, the battery weighs around 10kg, or 22lbs, plus other necessary equipment to connect the batteries together, to cool them, protect them in case of an accident, etc. It is hoped that energy density will increase approximately 10% per year for the next 10 years, more than doubling by 2020 and providing for cutting battery size and weight in half.

The next most critical attribute for an automotive battery is the cycle count. This is measured in the number of complete battery cycles until the battery can only hold 80% of its original capacity. A complete battery cycle is when the battery has been discharged and charged at its full capacity. So discharging a battery 50% twice or 33% three times, both equal one complete cycle. Batteries also have an expected calendar life, but this isn’t related to the cycle count.

To extend the the cycle count of the battery, you can use a smaller depth of discharge. The Chevy Volt is the perfect example. It has a 16kWh battery but only will use 8kWh, charging to 85% total capacity and discharging down to 35% for daily driving on electricity. Using only 50% of the battery capacity doubles the number of recharges the battery can withstand until it can only store 80% of original capacity.

The lithium ion battery in your laptop has a life of 18-24 months, and a cycle count of around 300. This isn’t anywhere near suitable for use in electric vehicles, so different battery formulations that last longer and have higher cycle counts are being developed. No one will really know what the Volt’s batteries are capable of until they start selling units, but the battery would need to be capable of around 3,750 recharges (a cycle count of 1,875).

California regulations require electric cars to have batteries that are warrantied for 10 years and 150,000 miles, so automakers are targeting those figures. Granted you have to live in CA or have bought it there to be covered, but because the market is so large automakers really have no choice but to match those warranty numbers.

Finally in this battery tutorial is the charge/discharge, or sometime just called the charge rate, noted as nC where n is an integer (1C, 2C, 6C). This can have an affect on the cycle count – the faster you charge and discharge the battery, the fewer cycles it is capable of. 1C is charging the battery so it will recharge in 1 hour – so an 11Ah battery charged at 11A (at the cell nominal voltage) is being charged at 1C, 22A would be 2C, and 66A would be 6C. Adding up all the cells in a battery pack would tell you what the total current the motor would be capable of receiving.

So thats it as far as this battery tutorial goes.